Hook &/ Rake Angle

Blade Geometry
Positive Hook &/ Rake Angle blade
160X20X36ZX1.8 kerf

Hook &/ Rake Angle: Positive or Negative?  The amount of forward or backward lean of the teeth on a blade in relation to it’s direction of rotation. It varies amongst manufacturers; typically anything from -6 to 25 degrees.
Usually a 20 to 25 degrees Hook &/ Rake Angle blade will be quite aggressive (very fast cutting speed) , whilst a 10 to 15 degrees would be much less; they would suit a ripping blade to process lengths of timber efficiently. Whereas a Negative Hook &/ Rake Angle blade ( slower cutting speed & thus less aggressive) would be favoured for processing dense materials such as metals, plastics & hardwoods.
Also worth noting is which machine is the blade meant for. Ideally all mitre saws & overhead types (radial arm saws) should use a Negative Hook &/ Rake Angle blade as the cutting pressure exerted on the material is towards the turn table rather than trying to lift the material away from it as with a Positive Hook &/ Rake Angle blade thus making for safer processing.
On the other hand a Positive Hook &/ Rake Angle blade is safer in a table saw where the blade’s teeth have a tendency to clamp the material into the table’s surface. Whereas a Negative Hook &/ Rake Angle blade will want to push the material upwards unless some sort of outside pressure is exerted on top of the material (Feather boards, feeding rollers)
For hand held circular saws; what matters is the correct blade for the task at hand. A blade with say a 15 degrees hook angle will cut reasonably fast with a clean cut underneath the work piece & some tear out on top; where as one with -5 degrees will be somewhat slower to go through the material but generally yield a better finish with less tear out on top of the work. Always let the blade do it’s work at it’s intended design, there is no need to force the machine as the quality of finish will suffer. The same is true if you go too slow with a high tooth count blade; this may give rise to burning marks.